Fiberoptic Fluorescence Detection Of Low Level Porphyrin Concentrations In Occult Metastases Of Lymph Nodes

Thomas S. Mang; Carolyn McGinnis; William R. Potter

doi:10.1117/12.952135

15 June 1989 Fiberoptic Fluorescence Detection Of Low Level Porphyrin Concentrations In Occult Metastases Of Lymph Nodes

Thomas S. Mang, Carolyn McGinnis, William R. Potter

Author Affiliations +

Proceedings Volume 1067, Optical Fibers in Medicine IV; (1989) https://doi.org/10.1117/12.952135
Event: OE/LASE '89, 1989, Los Angeles, CA, United States

Abstract

The newest developments in the evaluation of fluorescence detection in photodynamic therapy deal with the ability to distinguish tissue autofluorescence from that of injected photosensitizers. The ability to make this distinction as well as detect fluorescence slightly above background emanating from occult metastases is paramount for the diagnosis of disease. The delivery of light to excite and detect background fluorescence as well as photosensitizer fluorescence in tissues has been accomplished using two HeNe lasers emitting at 632.8 nm and 612 nm delivered through a single quartz fiber optic. Chopping at different frequencies, contributions of fluorescence may be separated. Fluorescence is picked up via a 400 micron quartz fiber optic positioned appropriately near the target tissue. Extraction procedures to quantitate Photofrino II concentration in tissues correlated with fluorescence measurements from instrumentation developed for in vivo fluorimetry were applied for the detection of low drug levels in occult metastases of the lymph nodes. These techniques have been initially applied to detect low levels of drug in DRA mice bearing the SMT-F tumor, which has been extensively studied in our laboratory. The data show the ability of the techniques to detect very low levels of porphyrin in the tumors after low, non-therapeutic doses of injected photosensitizer. The Pollard rat prostatic adenocarcinoma (PA-III) model was chosen for this study because of its characteristic pattern of metastases involving only ipsilateral lymph nodes. Early studies on this lymph node model have shown the ability of the detection device to measure low levels of drug in non-palpable occult metastases in the nodes. The findings show that the detection of small numbers of metastatic cells is possible (<100 cells) with injected DHE doses of 0.25 mg/kg.

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Thomas S. Mang, Carolyn McGinnis, and William R. Potter "Fiberoptic Fluorescence Detection Of Low Level Porphyrin Concentrations In Occult Metastases Of Lymph Nodes", Proc. SPIE 1067, Optical Fibers in Medicine IV, (15 June 1989); https://doi.org/10.1117/12.952135

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